Sentence Correction

Some officials both at the Treasury Department and the Securities and Exchange Commission recently said in off-the-record conversations that it may be a good idea to require that all large and highly leveraged banks should decrease their debt and should increase their asset base.
A) to require that all large and highly leveraged banks should decrease their debt and should increase their asset base
B) requiring that all large and highly leveraged banks decrease their debt and increase their asset base
C) to require of all large and highly leveraged banks the decreasing of debt and an increase in their asset base
D) requiring that all large and highly leveraged banks to decrease their debt and to increase their asset base
E) to require all large and highly leveraged banks to decrease their debt and increase their asset base

I have following doubts:
1. What is the difference between 'requiring' and 'to require'?
2. How to use infinitive form of verb (to require, to decrease) in context of this question?
3. Is there idiom usage in B, D and E? Which one is correct?
B: requiring that X decrease
D: requiring that X to decrease
E: to require X to decrease